TY - JOUR
T1 - Neuroanatomical aspects of mydriatic action of morphine in rats
AU - Kamenetsky, S.
AU - Rabinowitz, R.
AU - Urca, G.
AU - Korczyn, A. D.
PY - 1997/10
Y1 - 1997/10
N2 - Morphine causes mydriasis in rats. In order to investigate whether this effect is due to direct inhibition of preganglionic pupilloconstrictor neurons in the Edinger-Westphal nucleus (EWN), we injected opiate agonists into the EWN in male albino Charles River rats. Bilateral stereotactic microinjections of morphine (10, 20, 30, 40 μg/side) inhibited spinal nociceptive reflexes and caused pronounced catalepsy, but had no effect on pupillary size. The powerful opiate agonist, fentanyl, also elicited analgesia and catalepsy, when given in doses of 5 and 10 μg/side, but no dose of fentanyl up to 10 μg/side induced mydriasis. Naloxone (10 μg/side), given into the EWN, effectively antagonized inhibition of the tail-flick response induced by subcutaneously administered morphine (30 mg/kg), but had no effect on the cataleptic and mydriatic actions of systemic morphine. These results indicate that, in the rat, morphine-induced mydriasis is not accounted for by a direct action on the EWN.
AB - Morphine causes mydriasis in rats. In order to investigate whether this effect is due to direct inhibition of preganglionic pupilloconstrictor neurons in the Edinger-Westphal nucleus (EWN), we injected opiate agonists into the EWN in male albino Charles River rats. Bilateral stereotactic microinjections of morphine (10, 20, 30, 40 μg/side) inhibited spinal nociceptive reflexes and caused pronounced catalepsy, but had no effect on pupillary size. The powerful opiate agonist, fentanyl, also elicited analgesia and catalepsy, when given in doses of 5 and 10 μg/side, but no dose of fentanyl up to 10 μg/side induced mydriasis. Naloxone (10 μg/side), given into the EWN, effectively antagonized inhibition of the tail-flick response induced by subcutaneously administered morphine (30 mg/kg), but had no effect on the cataleptic and mydriatic actions of systemic morphine. These results indicate that, in the rat, morphine-induced mydriasis is not accounted for by a direct action on the EWN.
UR - http://www.scopus.com/inward/record.url?scp=0031431489&partnerID=8YFLogxK
U2 - 10.1089/jop.1997.13.405
DO - 10.1089/jop.1997.13.405
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:0031431489
SN - 1080-7683
VL - 13
SP - 405
EP - 413
JO - Journal of Ocular Pharmacology and Therapeutics
JF - Journal of Ocular Pharmacology and Therapeutics
IS - 5
ER -